Method and system for acquiring high frequency carrier in a wireless communication network

ABSTRACT

A method and system for acquiring mmWave carrier in a wireless communication network is disclosed. In one embodiment, an MS acquires a low frequency carrier and then acquires the high frequency carrier. Since the low frequency carrier and the high frequency carrier are transmitted by same BS, the BS provides assistance information on the acquired low frequency carrier to the MS to acquire a synchronization signal which is transmitted on a high frequency carrier using beamforming. The assistance information includes synchronization signal beam time slots, synchronization signal beams which the MS needs to search, beam ID and so on. Based on the assistance information, the MS monitors the high frequency carrier to search and acquire the synchronization beam signal transmitted on the high frequency carrier. The MS determines the beam ID of the received synchronization beam signal and reports to the BS on the low frequency carrier.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of application Ser. No.15/474,602, filed Mar. 30, 2017, which is a continuation of applicationSer. No. 14/262,474, filed Apr. 25, 2014, now U.S. Pat. No. 10,292,123,which claims priority under 35 U.S.C. § 119 to Indian ProvisionalApplication No. 1815/CHE/2013, filed Apr. 25, 2013, and Indian PatentApplication No. 1815/CHE/2013, filed Apr. 15, 2014, the disclosures ofwhich are herein incorporated by reference in their entirety

BACKGROUND 1. Field

The present invention relates to the field of wireless communicationsystems, and more particularly relates to method and system foracquiring high frequency carrier in a wireless communication network.

2. Description of Related Art

In the recent years several broadband wireless technologies have beendeveloped to meet the growing number of broadband subscribers and toprovide more and better applications and services. The 3rd GenerationPartnership Project 2 (3GPP2) developed Code Division Multiple Access2000 (CDMA 2000), 1× Evolution Data Optimized (1×EVDO) and Ultra MobileBroadband (UMB) systems. The 3rd Generation Partnership Project (3GPP)developed Wideband Code Division Multiple Access (WCDMA), High SpeedPacket Access (HSPA) and Long Term Evolution (LTE) systems. TheInstitute of Electrical and Electronics Engineers developed MobileWorldwide Interoperability for Microwave Access (WiMAX) systems. As moreand more people become users of mobile communication systems and moreand more services are provided over these systems, there can be anincreasing need for a mobile communication system with large capacity,high throughput, lower latency, and better reliability.

SUMMARY

To address the above-discussed needs, it is a primary object to providea system and method for acquiring a high frequency carrier in acommunication network. A first example of a method of acquiring a highfrequency carrier in a communication network is disclosed herein. Themethod includes receiving second carrier acquisition information,wherein the acquisition information comprises at least one ofinformation about one or more synchronization signal beams beingtransmitted in each sector of a base station (BS), time intervalinformation of a second carrier in which the synchronization signalbeams are transmitted by the BS, synchronization signal beam informationof the one or more synchronization signal beams being transmitted by theBS in each of an indicated time interval, information about the one ormore synchronization signal beams to be monitored by the mobile station(MS) and information about the one or more time intervals to bemonitored by the MS, wherein the second carrier acquisition informationis received by the MS from the BS on a first carrier, determining theone or more synchronization signal beams for monitoring by the MSamongst a plurality of synchronization signal beams transmitted on thesecond carrier, determining the time intervals by the MS when thedetermined synchronization signal beams are being transmitted on thesecond carrier, and monitoring the second carrier at the determined timeintervals by the MS to search and acquire the synchronization signaltransmitted on the second carrier.

A second example of a method of acquiring a high frequency carrier in acommunication network is disclosed herein. The method includestransmitting by a base station (BS) second carrier acquisitioninformation wherein the acquisition information comprises at least oneof information about one or more synchronization signal beams beingtransmitted in each sector of the BS, time interval information of asecond carrier in which synchronization signal beams are beingtransmitted by BS, synchronization signal beam information of one ormore synchronization signal beams being transmitted by the BS in each ofan indicated time interval, information about the one or moresynchronization signal beams to be monitored by a mobile station (MS)and information about the one or more time intervals to be monitored bythe MS, wherein the second carrier acquisition information istransmitted by the BS on a first carrier.

A third example of a system for acquiring a high frequency carrier in acommunication network is disclosed herein. The system includes a mobilestation (MS) configured to receive second carrier acquisitioninformation comprising at least one of information about one or moresynchronization signal beams being transmitted in each sector of a basestation (BS), time interval information of a second carrier in which thesynchronization signal beams are being transmitted by the BS,synchronization signal beam information of the one or moresynchronization signal beams being transmitted by the BS in each of anindicated time interval, information about the one or moresynchronization signal beams to be monitored by the MS and informationabout the one or more time intervals to be monitored by the MS, whereinthe second carrier acquisition information is received by the MS fromthe BS on a first carrier. The MS is also configured to determine theone or more synchronization signal beams for monitoring amongst aplurality of synchronization signal beams transmitted on the secondcarrier. The MS is further configured to determine the time intervalswhen the determined synchronization signal beams are transmitted on thesecond carrier. The MS is configured to monitor the second carrier atthe determined time intervals to search and acquire the synchronizationsignal transmitted on the second carrier.

A fourth example of a system for acquiring a high frequency carrier in acommunication network is disclosed herein. The system includes a basestation (BS) configured to transmit second carrier acquisitioninformation comprising at least one of information about one or moresynchronization signal beams being transmitted in each sector of the BS,time interval information of a second carrier in which synchronizationsignal beams are being transmitted by the BS, synchronization signalbeam information of one or more synchronization signal beams beingtransmitted by the BS in each of an indicated time interval, informationabout the one or more synchronization signal beams to be monitored by amobile station (MS) and information about the one or more time intervalsto be monitored by the MS, wherein the second carrier acquisitioninformation is transmitted by the BS on a first carrier.

Before undertaking the DETAILED DESCRIPTION below, it may beadvantageous to set forth definitions of certain words and phrases usedthroughout this patent document: the terms “include” and “comprise,” aswell as derivatives thereof, mean inclusion without limitation; the term“or,” is inclusive, meaning and/or; the phrases “associated with” and“associated therewith,” as well as derivatives thereof, may mean toinclude, be included within, interconnect with, contain, be containedwithin, connect to or with, couple to or with, be communicable with,cooperate with, interleave, juxtapose, be proximate to, be bound to orwith, have, have a property of, or the like; and the term “controller”means any device, system or part thereof that controls at least oneoperation, such a device may be implemented in hardware, firmware orsoftware, or some combination of at least two of the same. It should benoted that the functionality associated with any particular controllermay be centralized or distributed, whether locally or remotely.Definitions for certain words and phrases are provided throughout thispatent document, those of ordinary skill in the art should understandthat in many, if not most instances, such definitions apply to prior, aswell as future uses of such defined words and phrases.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and itsadvantages, reference is now made to the following description taken inconjunction with the accompanying drawings, in which like referencenumerals represent like parts:

FIG. 1 is an example schematic representation of an asymmetric multibandmulticarrier system according to this disclosure;

FIGS. 2A to 2D are examples schematic representations of SynchronizationChannel (SCH)/Broadcast Channel (BCH) transmission and reception usingbeam forming in a standalone high frequency carrier system according tothis disclosure;

FIG. 3A to 3C are examples timing diagrams depicting timingsynchronization between a low frequency and a high frequency carrier inthe asymmetric multiband multicarrier system according to thisdisclosure;

FIG. 4A is an example system for acquiring a high frequency carrier in acommunication network according to this disclosure;

FIG. 4B is an example schematic representation depicting informationtransmitted by a Base station (BS) to assist a Mobile station (MS) forsearching and acquiring a high frequency carrier according to thisdisclosure;

FIG. 5 is an example flow diagram of a method of acquiring a highfrequency carrier in a communication network according to thisdisclosure;

FIG. 6 is an example flow diagram of a method of acquiring highfrequency carrier in a communication network when a Base station (BS)broadcasts information associated with synchronization signal beamstransmitted in each sector according to this disclosure;

FIG. 7 is an example flow diagram of a method of acquiring a highfrequency carrier in a communication network when a Base station (BS)unicasts information associated with synchronization signal beamstransmitted in each sector according to this disclosure;

FIG. 8 is an example flow diagram of a method of acquiring a highfrequency carrier in a communication network when a Base station (BS)broadcasts information regarding synchronization signal beamstransmitted in each sector according to this disclosure;

FIG. 9 is an example flow diagram of a method of acquiring a highfrequency carrier in a communication network when a Base station (BS)unicasts information associated with synchronization signal beamstransmitted in each sector according to this disclosure;

FIG. 10 is an example flow diagram of a method of acquiring a highfrequency carrier in a communication network when a BS broadcastsinformation regarding synchronization signal beams transmitted in eachsector according to this disclosure;

FIG. 11 is an example flow diagram of a method of acquiring a highfrequency carrier in a communication network when a BS unicastsinformation associated with synchronization signal beams transmitted ineach sector according to this disclosure;

FIG. 12 is an example flow diagram of a method of acquiring a highfrequency carrier in a communication network according to thisdisclosure;

FIG. 13 is an example flow diagram of a method of acquiring a highfrequency carrier in a communication network according to thisdisclosure;

FIG. 14 is an example flow diagram of a method of activating a highfrequency carrier according to this disclosure; and

FIG. 15 is an example flow diagram of a method of activating a highfrequency carrier according to this disclosure.

DETAILED DESCRIPTION

FIGS. 1-15 , discussed below, and the various embodiments used todescribe the principles of the present disclosure in this patentdocument are by way of illustration only and should not be construed inany way to limit the scope of the disclosure. Those skilled in the artwill understand that the principles of the present disclosure may beimplemented in any suitably arranged communication system. Theembodiments of the present invention will now be described in detailwith reference to the accompanying drawings. However, the presentinvention is not limited to the embodiments. The present invention canbe modified in various forms. Thus, the embodiments of the presentinvention are only provided to explain more clearly the presentinvention to the ordinarily skilled in the art of the present invention.In the accompanying drawings, like reference numerals are used toindicate like components.

The specification may refer to “an”, “one” or “some” embodiment(s) inseveral locations. This does not necessarily imply that each suchreference is to the same embodiment(s), or that the feature only appliesto a single embodiment. Single features of different embodiments mayalso be combined to provide other embodiments.

As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless expressly stated otherwise. Itwill be further understood that the terms “includes”, “comprises”,“including” and/or “comprising” when used in this specification, specifythe presence of stated features, integers, steps, operations, elementsand/or components, but do not preclude the presence or addition of oneor more other features integers, steps, operations, elements,components, and/or groups thereof. As used herein, the term “and/or”includes any and all combinations and arrangements of one or more of theassociated listed items.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure pertains. It willbe further understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

Super Mobile Broadband (SMB) system based on millimeter waves such asradio waves with wavelength in the range of 1 millimeter (mm) to 10 mm,which can correspond to a radio frequency of 30 Gigahertz (GHz) to 300GHz, can be a candidate for next generation mobile communicationtechnology as vast amount of spectrum is available in mmWave band. AnSMB network as introduced in paper titled “An introduction toMillimeter-Wave Broadband Systems” authored by Zhouyue Pi and FarooqKhan which is hereby incorporated by reference into this patent documentin its entirety can consist of multiple SMB base stations (BSs) thatcover a geographic area. In order to ensure good coverage, SMB basestations can be deployed with higher density than macro-cellular basestations. In general, roughly the same site-to-site distance asmicrocell or Pico-cell deployment in an urban environment can berecommended. The transmission and/or reception in an SMB system can bebased on narrow beams, which can suppress the interference fromneighbouring SMB base stations and can extend the range of an SMB link.However due to high path loss, heavy shadowing and rain attenuationreliable transmission at higher frequencies can be one of the key issuesthat need to be overcome in order to make the millimeter wave systems apractical reality.

The lower frequencies in cellular band having robust linkcharacteristics can be utilized together with higher frequencies inmmWave band to overcome the reliability issues in the SMB systems. In anasymmetric multiband multicarrier SMB network wherein the mobile station(MS) communicates with the communication network using asymmetricmultiband carriers comprising at least one low frequency carrier incellular band and at least one high frequency carrier in the mmWaveband. The primary carrier such as a carrier operating on low frequenciesand the secondary/extended carrier such as a carrier operating on highfrequencies can be transmitted by the same base station as illustratedin FIG. 1 . The base station can broadcast necessary information foridentifying, acquiring, and registering with the base station on the lowfrequency carrier. The high frequency with large bandwidth can be usedprimarily for providing the high data rates services to the mobileusers. Since the coverage of low frequency carrier and high frequencycarrier can be quite different, the MS may have to search and acquirethe high frequency carrier even if the MS has acquired the low frequencycarrier and has registered with the base station.

In a standalone system, the BS can communicate with MS using only a highfrequency carrier. At higher frequency, the propagation path loss can behigher and hence a propagation distance can be shorter. Beamformingtechniques can be used to decrease the propagation path loss and toincrease the propagation distance for communication at a higherfrequency. Beamforming can be classified into Transmission (TX)beamforming performed in a transmitting end and reception (RX)beamforming performed in a receiving end. In general, the TX beamformingcan increase directivity by allowing an area in which propagationreaches to be densely located in a specific direction by using aplurality of antennas. In this situation, aggregation of the pluralityof antennas can be referred to as an antenna array, and each antennaincluded in the array can be referred to as an array element.

The antenna array can be configured in various forms such as a lineararray, a planar array, and the like. The use of the TX beamforming canresult in the increase in the directivity of a signal, therebyincreasing a propagation distance. Further, since the signal is almostnot transmitted in a direction other than a directivity direction, asignal interference acting on another receiving end can be significantlydecreased. The receiving end can perform beamforming on a RX signal byusing a RX antenna array. The RX beamforming can increase the RX signalstrength transmitted in a specific direction by allowing propagation tobe concentrated in a specific direction, and can exclude a signaltransmitted in a direction other than the specific direction from the RXsignal, thereby providing an effect of blocking an interference signal.

The BS can transmit a synchronization signal through a SynchronizationChannel (SCH) which can assist an MS to detect the presence of a basestation (BS). The BS can also transmit the broadcast signal through aBroadcast Channel (BCH). The BCH can carry essential system informationwhich can enable the MS to have initial communication with the BS. TheSCH & BCH can be transmitted repetitively by performing beamforming onthe channels with different transmission beams wherein each TX beamtransmits the SCH and BCH in different directions. Because of hardwarelimitation (such as one antenna array is needed for one beam direction)the TX beams in different directions can be transmitted at differenttimes. The MS can use receive beamforming to detect the synchronizationsignal. MS can use multiple RX beams to detect the SCH transmissionusing multiple TX beams. Consider for example, SCH & BCH can betransmitted using 4 TX beams and MS can use 4 RX beams to search the SCH& BCH. 4 TX beams can be transmitted in four different time durations(such as slots) in a sub frame on the high frequency carrier asillustrated in FIG. 1 .

The MS can first configure the receiver antenna array to receive usingfirst Rx beam Rx1. The MS can receive and search for SCH for one subframe duration using first Rx beam Rx1 as illustrated in FIG. 2A. The MSthen can configure the receiver antenna array to receive using second Rxbeam Rx2 as illustrated in FIG. 2B. The MS can receive and search forSCH for one sub frame duration using second Rx beam Rx2. The sameprocedure can be repeated for Rx beam 3 and Rx beam 4 as illustrated inFIG. 2C and FIG. 2D. Based on the reception in four sub frames, the MScan determine the best TX and RX beam pair. During the initialacquisition of high frequency carrier, the MS may not be synchronizedwith the transmissions of the base station and hence may have tocontinuously process the received signals to detect the SCH. The MS mayalso have to determine the TX beam ID in order to report the best TXbeam to the BS. The TX beam ID can be indicated in the synchronizationsignal transmitted in SCH by scrambling the synchronizing signal withdifferent scrambling code for different TX beams. This can increase theprocessing effort by four times for the MS as the MS has to descramblethe received synchronization signal using four scrambling codes.Alternately the TX beam ID can be indicated as an information element inthe system information carried in BCH or by using the differentscrambling code for different TX beam transmitting the BCH. In this caseafter detecting the SCH, MS can receive the BCH to determine the TX beamID. This method can also increase the processing effort for the MS asthe MS can receive and decode the BCH.

In a system wherein the BS can communicate with the MS using lowfrequency carrier and high frequency carrier, the method of acquiringthe high frequency carrier as used in standalone system can beinefficient as explained above.

Therefore, there can be a need of method and system for acquiring a highfrequency carrier in a wireless communication network in order toovercome the limitation as discussed.

A method and system of acquiring a high frequency carrier (such as amillimeter (mm) Wave carrier) in a wireless communication network inwhich a base station communicates with a mobile station in the wirelesscommunication network using asymmetric multiband carriers including atleast one low frequency carrier in a cellular band and at least one highfrequency carrier in a mmWave band is disclosed herein.

FIG. 1 is an example schematic representation of an asymmetric multibandmulticarrier system 100 according to this disclosure. In an asymmetricmultiband multicarrier SMB network where a mobile station (MS) 101communicates with a wireless communication network using asymmetricmultiband carriers can comprise at least one low frequency carrier incellular band and at least one high frequency carrier in the mmWaveband, the primary carrier such as a carrier operating on low frequenciesand the secondary/extended carrier such as a carrier operating on highfrequencies can be transmitted by the same base station (BS) 102. Thebase station 102 can broadcast necessary information for identifying,acquiring and registering with the base station 102 on the low frequencycarrier. The high frequency with large bandwidth can be used primarilyfor providing the high data rates services to the mobile users. Sincethe coverage of low frequency carrier and high frequency carrier can bequite different the MS 101 may have to search and acquire the highfrequency carrier even if the MS 101 has acquired the low frequencycarrier and has registered with the base station 102.

In one embodiment, the low frequency carrier (which also can be referredto as 4G carrier or first carrier) and high frequency carrier (whichalso can be referred to as 5G carrier or second carrier in thedisclosure) can be transmitted in a time synchronized manner. Considerfor example that the transmission on a low frequency carrier can bedivided into fixed time intervals (or frames) wherein each time intervalis of one millisecond. Each frame can carry multiple OFDM symbols incase of OFDM based transmission on the low frequency carrier. Thetransmission on high frequency carrier can also be divided into fixedtime intervals (or frames) wherein each time interval is of onemillisecond. The time intervals on low frequency carrier and highfrequency carrier can be different in different embodiments or systems.Each frame on the high frequency carrier can be further divided intoslots wherein each slot carries one or more OFDM symbols in case of OFDMbased transmission on the high frequency carrier. In an embodiment, theframes of low frequency carrier and high frequency carrier can be timesynchronized as illustrated in FIG. 3A. In at least this embodiment, thelocation of the synchronization signal transmitted in a frame of highfrequency carrier can be determined using the ‘offset’ value from thestart of the frame. Alternately, the OFDM symbol in the low frequencycarrier can be synchronized with the slots in the high frequency carrieras illustrated in FIG. 3B. In at least this embodiment, if the SCHoccupies the entire slot, the location of SCH can be determined usingthe OFDM symbol duration. For example, SCH transmitted in slot 2 of highfrequency carrier can be 2 OFDM symbols away from the start of frame inlow frequency carrier. Alternately if SCH occupies few OFDM symbols inslot 2 then OFDM duration+offset can be used to determine the locationof SCH as illustrated in FIG. 3C.

As disclosed herein, the MS can first acquire the low frequency carrierand then can acquire the high frequency carrier as and when needed.Since the low frequency carrier and high frequency carrier can betransmitted by the same BS, the BS can assist the MS which has acquiredthe low frequency carrier and is registered with the BS. The BS canassist the MS to acquire the high frequency carrier or 5G carrier asfollows:

In an embodiment, the base station can inform the MS about the timeintervals in which the synchronization signal is transmitted on the highfrequency carrier. The synchronization signal can be transmitted usingbeamforming in multiple directions wherein one or more beamtransmissions are separated in time. The base station can transmit thisinformation to the MS on the low frequency carrier. This information canbe broadcasted or sent in a unicast manner to the MS. In an embodiment,the synchronization signal beam transmission time intervals on highfrequency carrier can be fixed in the system. In this case BS may notinform the MS about the time intervals in which the synchronizationsignal beam is transmitted on the high frequency carrier. The BS canalso inform the MS about the timing of synchronization signal beamtransmission on high frequency carrier with respect to timing on lowfrequency carrier. The information about the time intervals forsynchronization signal beam transmission can reduce the time the MS hasto monitor the high frequency carrier.

In an embodiment, the base station can also inform the MS about the IDof the synchronization signal beam transmitted in each of the indicatedtime intervals. Multiple synchronization signal beams can be transmitteddepending on TX beamforming capability of the BS. In case multiplesynchronization signal beams are transmitted at same time, thescrambling code or beam sequence used to distinguish the multiple beamscan also be informed to the MS. The BS can transmit this information tothe MS on the low frequency carrier. In an embodiment, there can be afixed mapping between the beam IDs and time intervals in which thesynchronization signal beam is transmitted. For example, if foursynchronization signal beams are transmitted in slot 1, slot 2, slot 3and slot 4, the beam ID for synchronization signal beam in slot 1 can beBeam ID1, the beam ID for synchronization signal beam in slot 2 can beBeam ID2, the beam ID for synchronization signal beam in slot 3 can beBeam ID3 and the beam ID for synchronization signal beam in slot 4 canbe Beam ID4. In another example, if two synchronization signal beams aretransmitted in slot 1 and two synchronization signal beams aretransmitted in slot 2 then beams in slot 1 can have beam ID1 and beamID2 while beams in slot 2 can have beam ID 3 and Beam ID 4. Scramblingcodes or beam sequences can be used to distinguish between two beams andbeam IDs in a slot. For example, scrambling code 1 or beam sequence 1can correspond to Beam ID1 and scrambling code 2 or beam sequence 2 cancorrespond to Beam ID2. The information about the synchronization signalbeam IDs can eliminate the need for the MS to read BCH information todetermine the Beam ID. It can also eliminate the need for the MS toidentify beam ID by descrambling the code used to transmit thesynchronization signal beam.

In an embodiment, the BS can inform the MS about the beams to besearched by it amongst the plurality of synchronization signal beamstransmitted by the BS. This information can be transmitted by the BS onthe low frequency carrier. The information about the specific beams tobe searched by the MS amongst the plurality of synchronization signalbeams can be determined as follows: The coverage of low frequencycarrier transmitted by the BS can be divided into multiple sectors. Eachof these sectors can have different cell IDs or can have the same cellIDs. Each of the plurality of synchronization signal beams transmittedon high frequency carrier can be mapped to one of these sectors.Consider for example that there can be six synchronization signal beamstransmitted on the high frequency carrier. Synchronization signal beam 1and beam 2 can be transmitted in an area covered by sector 1,synchronization signal beam 3 and beam 4 can be transmitted in an areacovered by sector 2, and synchronization signal beam 5 and beam 6 can betransmitted in an area covered by sector 3.

In an embodiment, when or after the MS acquires the low frequencycarrier and registers with the BS, both the BS and MS can be aware ofthe sector to which the MS is attached. Since the MS can be attached ona specific sector, the MS can search only for the synchronization signalbeams transmitted in the sector. In an embodiment, the BS can transmit(broadcasts or unicast) information about the sectors and beam IDs ineach sector. The MS can then determine the synchronization signal beamsit has to search. In an embodiment, BS can determine the synchronizationsignal beams the MS has to search based on the sector to which MS isattached. The BS can then inform the MS about the beams to be searchedby it amongst the plurality of synchronization signal beams on a lowfrequency carrier.

In an embodiment, the BS can determine a sector location of the MS basedon the antenna from which BS receives MS transmissions on a lowfrequency carrier. Each sector can have different antenna for reception.In an embodiment, the BS cam determine the synchronization signal beamsthe MS has to search based on the determined sector location of the MSusing the receive antenna. The BS can then inform the MS about the beamsto be searched by it amongst the plurality of synchronization signalbeams on the low frequency carrier.

In addition to synchronization signal beams of sector to which the MS isattached, some synchronization signal beams of neighboring sector canalso be monitored by the MS. The BS can inform these on the lowfrequency carrier to the MS.

The term “low frequency carrier”, “first carrier”, and “4G carrier” canbe used interchangeably throughout this disclosure. In an embodiment,the term “high frequency carrier”, “second carrier”, and “5G carrier”can also be used interchangeably throughout this disclosure.

FIG. 4A is an example block diagram of a system 400 for acquiring a highfrequency carrier in a communication network according to thisdisclosure. The system 400 can include at least one mobile station (MS)and at least one base station (BS). The at least one MS and the at leastone BS can be coupled to each other through a communication network 404.The MS can include, but is not limited to, a low frequency transceiver(Tx/Rx) module 401, a high frequency receiver (Rx) module 402, and ahigh frequency acquisition module 403. The BS can include, but is notlimited to, a low frequency transceiver (Tx/Rx) module 405, and a highfrequency transceiver (Tx/Rx) module 406.

FIG. 4B is an example in which information being transmitted by BS canassist the acquisition of a high frequency carrier depending on how thesynchronization signal is transmitted by the BS. The MS can be incoverage of the BS and can be attached to Sector 1 of the BS. The BScoverage can be divided into three sectors. There can be at least twomethods followed by the BS for transmitting the synchronization signalon a high frequency carrier. In a first method, a BS can transmit allthe beams of a synchronization signal in one sub frame of a highfrequency carrier. Each beam can be transmitted in different slots of asub frame. These steps can be repeated for other sub frames. In at leastthe first method, the MS can first configure the first RX beam RX1 andcan search for synchronization signal beams in sub frame 1 and then theMS can configure the second RX beam RX2 and can search forsynchronization signal beams in sub frame 2. In order to assist the MSin searching the synchronization signal, BS can provide one or more ofthe following information to MS:

SCH slots in SF: 0,2,4,6,8,10

Beam IDs in SCH slot: B2, B3, B4, B5, B0, B1

Current sector beam: B2, B3

Neighbouring beam of current sector: B4, B1

In a method, a BS can transmit one synchronization signal beam in onesub frame. Multiple transmissions of same synchronization signal beamcan be done in one sub frame. In at least the second method, the MS canuse both the RX beam RX1 and RX beam RX2 one after another in each subframe to search for synchronization signal. In order to assist the MS insearching the synchronization signal, the BS can provide one or more ofthe following information to MS:

SCH slots in SF: 0, 2,4,6,8

Number of TX beams: 6

Beam ID in SF: SF1 (B2), SF2(B3), SF3(B4), SF4(B5), SF5(B0), SF6(B1);Starting SF number of a group of 6 SFs is provided

Current sector beam: B2, B3

Neighbouring beam of current sector: B4, B1

FIG. 5 is an example flow diagram of a method of searching and acquiringa high frequency carrier in a communication network according to thisdisclosure. An MS can receive a trigger from a BS to search and acquirethe synchronization signal transmitted on the high frequency carrier orthe MS can decide on its own to search and acquire the synchronizationsignal transmitted on the high frequency carrier. In step 501, the MScan receive the high frequency carrier acquisition information from theBS on the low frequency carrier. The received high frequency carrieracquisition information can include at least one of information aboutone or more synchronization signal beams being transmitted in eachsector of the BS, time interval information of a high frequency carrierin which the synchronization signal beams are being transmitted by theBS, synchronization signal beam information of the one or moresynchronization signal beams being transmitted by the BS in each of anindicated time interval, information about the one or moresynchronization signal beams to be monitored by the MS, and informationabout the one or more time intervals to be monitored by the MS. Thesynchronization signal beam information can include at least one of abeam identifier and beam sequence corresponding to a beam. The highfrequency carrier acquisition information can include information toacquire the high frequency carrier of the BS to which the MS is attachedor to acquire the high frequency carrier of a neighbor BS or both. Thehigh frequency carrier acquisition information can be broadcasted by theBS. Alternately the high frequency carrier acquisition information canbe sent by the BS in dedicated signalling.

In step 502, the MS can determine the synchronization signal beams itneeds to monitor amongst the plurality of synchronization signal beamtransmitted on the high frequency carrier. The MS can monitor all thesynchronization signal beams transmitted by the BS. The MS can monitorsome of the synchronization signal beams transmitted on the highfrequency carrier. The MS can determine the one or more synchronizationsignal beams corresponding to the sector on which the MS is attachedwith the BS using the received high frequency carrier acquisitioninformation comprising information about the one or more synchronizationsignal beams being transmitted in each sector of BS. In an embodiment,the MS can monitor the synchronization signal beams indicated in thereceived second carrier acquisition information for MS monitoring. Thereceived synchronization signal beams information for MS monitoring inthe high frequency carrier acquisition information can be determined bythe BS based on the sector to which the MS is attached.

In step 503, the MS can determine the time intervals on the highfrequency carrier where the determined synchronization signal beams aretransmitted. In an embodiment, the time intervals of synchronizationsignal beam transmission and mapping between time intervals andsynchronization signal beams can be transmitted by the BS in highfrequency carrier acquisition information. The time intervalscorresponding to the determined synchronization signal beams can bedetermined using the received high frequency carrier acquisitioninformation comprising of time interval information of the secondcarrier in which the synchronization signal beams being transmitted bythe BS and the synchronization signal beam information of one or moresynchronization signal beams being transmitted by the BS in each of anindicated time interval. In an embodiment, the time intervals ofsynchronization signal beam transmission can be pre-defined and mappingbetween pre-defined time intervals and synchronization signal beams canbe transmitted by BS in high frequency carrier acquisition information.The time intervals corresponding to the determined synchronizationsignal beams can be determined using the received high frequency carrieracquisition information including synchronization signal beaminformation of one or more synchronization signal beams beingtransmitted by the BS in each of predefined time interval forsynchronization signal beam transmission on the second carrier. In anembodiment, the time intervals of synchronization signal beamtransmission and mapping between time intervals and synchronizationsignal beams can be predefined. The time intervals corresponding to thedetermined synchronization signal beams can be determined using thepredefined time intervals for synchronization signal beam transmissionand the predefined mapping between one or more synchronization signalbeams and the time interval for synchronization signal beamtransmission. In an embodiment, the MS can monitor the time intervalsindicated in the received second carrier acquisition information for MSmonitoring. The received time interval information for MS monitoring inthe high frequency carrier acquisition information can be determined bythe BS based on the sector to which the MS is attached.

In step 504, the MS can monitor the high frequency carrier at thedetermined time intervals to search and acquire the synchronizationsignal transmitted on the high frequency carrier.

In step 505, beam ID of the acquired synchronization signal beam can bedetermined. The beam ID of the successfully received synchronizationsignal beam can be determined based on at least one of the timeintervals in which the synchronization signal beam is received and thebeam sequence. The synchronization signal beam information comprising atleast one of beam ID and beam sequence of the successfully received oneor more synchronization signal beams can also be reported by the MS tothe BS on the low frequency carrier.

FIG. 6 is an example flow diagram of a method of searching and acquiringa high frequency carrier according to this disclosure.

The MS can acquire and register with the BS on a low frequency carrierat step 601. The BS can then broadcast high frequency carrieracquisition information to the MS on the acquired low frequency carrierat step 602. The information that is broadcasted can include, but is notlimited to, time interval information of the high frequency carrier inwhich synchronization signal beams are being transmitted by the BS,synchronization signal beam information of one or more synchronizationsignal beams being transmitted by the BS in each of an indicated timeinterval, and information about the one or more synchronization signalbeams being transmitted in each sector of the BS. The synchronizationsignal beam information can include at least one of a beam identifierand beam sequence corresponding to a beam.

Subsequently, the BS can send a high frequency carrier search command tothe MS on the acquired low frequency carrier at step 603.

FIG. 7 is an example flow diagram of a method of searching and acquiringa high frequency carrier according to this disclosure.

In an embodiment, the MS can acquire and register with the BS on a lowfrequency carrier at step 701. The BS can then unicast a high frequencycarrier search command to the MS at step 702. The search command caninclude, but is not limited to, time interval information of the highfrequency carrier in which synchronization signal beams are beingtransmitted by the BS, synchronization signal beam information of one ormore synchronization signal beams being transmitted by the BS in each ofan indicated time interval, and information about the one or moresynchronization signal beams being transmitted in each sector of the BS.The synchronization signal beam information can include at least one ofa beam identifier and beam sequence corresponding to a beam.

In an embodiment, the MS can acquire and register with a BS on a lowfrequency carrier at step 701. The MS can then send a high frequencycarrier search request to the BS at step 703. The BS can in returnprovide a high frequency carrier search response to the MS at step 704.The search response can include, but is not limited to, time intervalinformation of the high frequency carrier in which synchronizationsignal beams are being transmitted by the BS, synchronization signalbeam information of one or more synchronization signal beams beingtransmitted by the BS in each of an indicated time interval, andinformation about the one or more synchronization signal beams beingtransmitted in each sector of the BS. The synchronization signal beaminformation can include at least one of a beam identifier and beamsequence corresponding to a beam.

FIG. 8 is an example flow diagram of a method of searching and acquiringa high frequency carrier in a communication network according to thisdisclosure where the time slots used for synchronization signal beamsare fixed in the communication network.

In an embodiment, the MS can acquire and register with the BS on the lowfrequency carrier at step 801. The BS can then broadcast high frequencycarrier acquisition information to the MS on the acquired low frequencycarrier at step 802. The information can include but is not limited to,synchronization signal beam information of one or more synchronizationsignal beams being transmitted by the BS in the pre-defined timeintervals for synchronization signal transmission and information aboutthe one or more synchronization signal beams being transmitted in eachsector of the BS. The synchronization signal beam information caninclude at least one of a beam identifier and beam sequencecorresponding to a beam. Subsequently, the BS can send a high frequencycarrier search command to the MS on the acquired low frequency carrierat step 803.

FIG. 9 is an example flow diagram of a method of searching and acquiringa high frequency carrier, according to this disclosure where the timeslots used for synchronization signal beams are fixed in thecommunication network.

In an embodiment, the MS can acquire and register with the BS on the lowfrequency carrier at step 901. The BS can then send a high frequencycarrier search command to the MS on the acquired low frequency carrierat step 902. The search command can include but is not limited to,synchronization signal beam information of one or more synchronizationsignal beams being transmitted by the BS in the pre-defined timeintervals for synchronization signal transmission and information aboutthe one or more synchronization signal beams being transmitted in eachsector of the BS. The synchronization signal beam information caninclude at least one of a beam identifier and beam sequencecorresponding to a beam.

In an embodiment, the MS can acquire and register with the BS on the lowfrequency carrier at step 901. The MS can then send a high frequencycarrier search request to the BS on the acquired low frequency carrierat step 903. Subsequently, the BS can provide a high frequency carriersearch response to the MS on the acquired low frequency carrier at step904. The search response can include, but is not limited to,synchronization signal beam information transmitted in each sector, andbeam IDs of high frequency synchronization signal beams transmitted ineach sector.

FIG. 10 is an example flow diagram of a method of searching andacquiring a high frequency carrier according to this disclosure where afixed mapping is provided between the beam ID and the synchronizationsignal slots. In at least this embodiment, the time slots used forsynchronization signal beams can also be fixed in the communicationnetwork.

In an embodiment, the MS can acquire and register with the BS on the lowfrequency carrier at step 1001. The BS can then broadcast high frequencycarrier acquisition information to the MS on the acquired low frequencycarrier at step 1002. The information can include, but is not limited tosynchronization signal beam information transmitted in each sector.

In an embodiment, the BS can send a high frequency carrier searchcommand to the MS on the acquired low frequency carrier at step 1003.

FIG. 11 is an example flow diagram of a method of searching andacquiring a high frequency carrier according to this disclosure where afixed mapping is provided between the beam ID and the synchronizationsignal slots. In at least this embodiment, the time slots used forsynchronization signal beams can also be fixed in the communicationnetwork.

In an embodiment, the MS can acquire and register with the BS on the lowfrequency carrier at step 1101. The BS can then unicast a high frequencycarrier search command to the MS on the acquired low frequency carrierat step 1102. The search command can include, but is not limited to,synchronization signal beam information transmitted in each sector.

In an embodiment, the MS can acquire and register with the BS on the lowfrequency carrier at step 1101. The MS can then send a high frequencycarrier search request to the BS on the acquired low frequency carrierat step 1103. Subsequently, the BS can provide a high frequency carriersearch response to the MS on the acquired low frequency carrier at step1104. The search response can include but is not limited to,synchronization signal beam information transmitted in each sector.

FIG. 12 is an example flow diagram of a method of searching andacquiring a high frequency carrier in a communication network accordingto this disclosure. In at least this embodiment, the BS can determinetime slots of the high frequency carrier during which the MS monitorsthe high frequency carrier for the synchronization signal beams. Thetime slots used for synchronization signal beams can be fixed in thecommunication network. The beam IDs of synchronization signal beams canbe determined using the mapping between the time slot and beam ID. Asillustrated in FIG. 12 , the mapping can be fixed mapping.

In an embodiment, the MS can acquire and register with the BS on a lowfrequency carrier at step 1201. The MS can then send a high frequencycarrier search request at step 1202. Subsequently, the BS can determinesynchronization signal beams corresponding to a sector to which the MSis attached at step 1203. Later, the BS can send a high frequencycarrier search response to the MS at step 1204. Here, the high frequencycarrier search response can include synchronization signal beams tosearch and optionally beam ID and a time slot of a high frequencycarrier that the MS needs to monitor for receiving synchronizationsignal beams.

FIG. 13 is an example flow diagram of a method of searching andacquiring a high frequency carrier according to this disclosure. In atleast this embodiment, the MS can acquire and register with the BS on alow frequency carrier at step 1301. The BS can then determinesynchronization beams corresponding to the sector to which MS isattached at step 1302 and can send a high frequency carrier searchcommand to the MS at step 1303. The high frequency search command caninclude but is not limited to, synchronization signal beams to searchand a time slot of a high frequency carrier that the MS needs to monitorfor receiving synchronization signals.

Further, a high frequency carrier search result can be provided from theMS to the BS. The search result can include, but is not limited to, acarrier frequency, a beam ID of a synchronization signal beam received,beamforming capabilities, and the like.

FIG. 14 is an example of triggering of the activation of a highfrequency carrier according to this disclosure. The MS can initiate aconnection and transmit a connection request with QoS parameters for therequested connection. The BS can determine whether the QoS requestedrequires a high frequency carrier (or 5G carrier) or not. The BS canalso determine if the MS/BS supports 5G carrier capability or not. The5G carrier operation can be complex and power consuming. The 5G carriersmay be activated only if the QoS requested can only be met by the 5Gcarrier. The BS can be aware of MS's 5G capability in at least one ofthe following ways: 1) The MS can send this information during theregistration. 2) The MS can send this information along with connectionrequest. If the BS/MS can support 5G capability and QoS requestedrequires the 5G carrier then the BS can send the 5G carrier acquisitionrequest message with information about the 5G carrier parameters such asa carrier frequency, a frequency band, beamforming parameters, and thelike. The MS can acquire the 5G carrier based on information receivedfrom the BS and can send the 5G carrier acquisition response to the MS.On receiving the 5G carrier acquisition response, the BS can send aconnection response to the MS. The BS can indicate if the connectionrequest is accepted or not. If accepted, the BS can also indicate theQoS parameters depending on whether the 5G carrier was acquired or not.If the requested QoS required the 5G carrier and the 5G carrier was notacquired by MS, the BS can downgrade the QoS of connection or may rejectthe connection. An example of an activation of the 5G carrier whenconnection request is initiated by BS is illustrated in FIG. 15 .

In an embodiment, the BS can always transmit the synchronization signalusing beamforming. In an embodiment, the BS can transmit thesynchronization signal beam(s) in a sector based on the MS location. Ifthere is an MS attached to a sector of the BS on the low frequencycarrier then only BS can transmit one or more synchronization signalbeam of that sector. One or more synchronization signal beams in aneighbouring sector of the sector to which the MS is attached on lowfrequency carrier can also be transmitted on high frequency carrier.

In an embodiment, the BS can dynamically decide the synchronizationsignal slots for the beams based on a number of beams enabled fortransmission from the BS. For example, consider 4 synchronization signalbeams that can be used on a high frequency carrier. If allsynchronization signal beams are switched on, beam 1, beam 2, beam 3 andBeam 4 can be transmitted in slots T1, T2, T3 and T4 respectively (T1:B1, T2: B2, T3: B3, T4: B4). If beam 2 and beam 3 are switched off asthere is no MS in those sectors, the transmission slot of beam 4 can bechanged from slot T4 to T2 (T1: B1, T2: B4, T3: No Tx, T4: No Tx)

The methods explained in this disclosure can also be used for searchinga high frequency carrier of not only the BS to which the MS is attachedbut also of a neighboring BS.

Although the present disclosure has been described with an exemplaryembodiment, various changes and modifications may be suggested to oneskilled in the art. It is intended that the present disclosure encompasssuch changes and modifications as fall within the scope of the appendedclaims.

What is claimed is:
 1. A method for communicating by a terminal througha first cell and a second cell in a wireless communication system, themethod comprising: receiving, on the first cell, information related toone or more synchronization signals including timing configurationinformation for receiving the one or more synchronization signals on thesecond cell by the terminal and information indicating one or more beamsthrough which the one or more synchronization signals are transmitted onthe second cell, wherein the timing configuration information forreceiving the one or more synchronization signals on the second cellcomprises information related to a start subframe of a duration forreceiving the one or more synchronization signals; performingmeasurement of a synchronization signal on the second cell based on theinformation related to the one or more synchronization signals; andtransmitting, to a base station (BS), a report of the measurement,wherein a carrier frequency of the first cell is lower than a carrierfrequency of the second cell.
 2. The method of claim 1, wherein theduration for receiving the one or more synchronization signals includesat least one subframe.
 3. The method of claim 1, further comprisingreceiving information indicating one or more time intervals forreceiving the one or more synchronization signals on the second cell,which is broadcast by the BS.
 4. The method of claim 1, wherein thereport of the measurement comprises information for identifying at leastone beam related to the measured synchronization signal.
 5. A terminalfor communicating through a first cell and a second cell in a wirelesscommunication system, the terminal comprising: a transceiver; and acontroller coupled to the transceiver, wherein the controller isconfigured to: receive, on the first cell, information related to one ormore synchronization signals including timing configuration informationfor receiving the one or more synchronization signals on the second cellby the terminal and information indicating one or more beams throughwhich the one or more synchronization signals are transmitted on thesecond cell, wherein the timing configuration information for receivingthe one or more synchronization signals on the second cell comprisesinformation related to a start subframe of a duration for receiving theone or more synchronization signals, perform measurement of asynchronization signal on the second cell based on the informationrelated to the one or more synchronization signals, and transmit, to abase station (BS), a report of the measurement, wherein a carrierfrequency of the first cell is lower than a carrier frequency of thesecond cell.
 6. The terminal of claim 5, wherein the duration forreceiving the one or more synchronization signals includes at least onesubframe.
 7. The terminal of claim 5, wherein the controller is furtherconfigured to receive information indicating one or more time intervalsfor receiving the one or more synchronization signals on the secondcell, which is broadcast by the BS.
 8. The terminal of claim 5, whereinthe report of the measurement comprises information for identifying atleast one beam related to the measured synchronization signal.
 9. Amethod for communicating with a terminal by a base station (BS) in awireless communication system, the method comprising: transmitting, on afirst cell of the BS, information related to one or more synchronizationsignals including timing configuration information for receiving the oneor more synchronization signals on a second cell by the terminal andinformation indicating one or more beams through which the one or moresynchronization signals are transmitted on the second cell, wherein forreceiving the one or more synchronization signals on the second cellcomprises information related to a start subframe of a duration forreceiving the one or more synchronization signals; and receiving, fromthe terminal, a report of a measurement on a synchronization signaltransmitted on the second cell, wherein the measurement is performed bythe terminal based on the information related to the one or moresynchronization signals, wherein a carrier frequency of the first cellis lower than a carrier frequency of the second cell.
 10. The method ofclaim 9, wherein the duration for receiving the one or moresynchronization signals includes at least one subframe.
 11. The methodof claim 9, further comprising broadcasting information indicating oneor more time intervals for receiving the one or more synchronizationsignals on the second cell.
 12. The method of claim 9, wherein thereport of the measurement comprises information for identifying at leastone beam related to the measured synchronization signal.
 13. A basestation (BS) for communicating with a terminal in a wirelesscommunication system, the BS comprising: a transceiver; and a controllercoupled to the transceiver, wherein the controller is configured to:transmit, on a first cell of the BS, information related to one or moresynchronization signals including timing configuration information forreceiving the one or more synchronization signals on a second cell bythe terminal and information indicating one or more beams through whichthe one or more synchronization signals are transmitted on the secondcell, wherein the timing configuration information for receiving the oneor more synchronization signals on the second cell comprises informationrelated to a start subframe of a duration for receiving the one or moresynchronization signals, and receive, from the terminal, a report of ameasurement on a synchronization signal transmitted on the second cell,wherein the measurement is performed by the terminal based on theinformation related to the one or more synchronization signals, whereina carrier frequency of the first cell is lower than a carrier frequencyof the second cell.
 14. The BS of claim 13, wherein the duration forreceiving the one or more synchronization signals includes at least onesubframe.
 15. The BS of claim 13, wherein the controller is furtherconfigured to broadcast information indicating one or more timeintervals for receiving the one or more synchronization signals on thesecond cell.
 16. The BS of claim 13, wherein the report of themeasurement comprises information for identifying at least one beamrelated to the measured synchronization signal.